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- To: firstname.lastname@example.org
- Subject: symbol-macrolet
- From: Gregor.pa@Xerox.COM
- Date: Thu, 19 Nov 87 17:13 PST
- Line-fold: no
I suppose we should say explicitly that the symbol macros are recorded
in the macroexpansion environment so that macroexpand-1 of a symbol
which is a symbol-macro will expand it.
In the text in my draft, this would correspond to including something
like the following in remarks.
Within the body of symbol-macrolet the macroexpansion environment is
augmented to include a symbol-macro definition for the symbol. When
given the symbol and the environment as arguments, macroexpand-1 will
return the expansion. This means that a macro which appears in the
scope of symbol-macrolet can use macroexpand-1 to determine whether or
not a symbol names a symbol macro; this is particularly useful for
macros which want to determine whether or not their argument is a
(defmacro ^2 (form &optional environment)
(if (and (symbolp form)
(eq (macroexpand-1 form) environment))
`(* ,form ,form)
`(expt ,form 2)))
This is a pretty lame example. Hopefully we can come up with something
else that is as simple but more compelling.
Also, we may want to mention explicitly the zetalisp macro once-only.